Structural Diversity\nand Tunable Luminescent Properties\nof Zn(II) Metal–Organic Frameworks with Terephthalate and 4,7-Di(1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole\nLinkers

A series of new coordination polymers (CPs) [Zn(tr<sub>2</sub>btd)(bdc)]<sub><i>n</i></sub> (compound <b>1</b>), {[Zn<sub>2</sub>(tr<sub>2</sub>btd)<sub>2</sub>(bdc)<sub>2</sub>]·MeCN}<sub><i>n</i></sub> (compound <b>2</b>), {[Zn<sub>3</sub>(tr<sub>2</sub>btd)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>(bdc)<sub>3</sub>]·H<sub>2</sub>O}<sub><i>n</i></sub> (compound <b>3</b>), and [Zn(tr<sub>2</sub>btd)<sub>2</sub>(bdc)]<sub><i>n</i></sub> (compound <b>4</b>) were prepared from the\nsame starting materials under different reaction conditions. Compounds <b>1–3</b> demonstrated luminescent sensing properties toward\nGa<sup>3+</sup> cations with the limits of detection in a low micromolar\nrange, 1.6, 6.1, and 1.8 μM, respectively. Careful comparison\nof the crystal structures of the four synthesized CPs suggests that\nthe packing features and intermolecular interactions strongly influence\nthe luminescent and sensing properties. The luminescence sensing response\nwas attributed to the absorption enhancement upon the interaction\nof metal–organic framework with Ga<sup>3+</sup> via the nitrogen\natoms at positions 4 of 1,2,4-triazole rings.